An online resource based on the award-winning nature guide

Nocturnal Animals

Beavers Gathering & Storing Winter Food Supply

10-15-13  beaver winter food supply pile 292(Part 3 of 3 Beaver posts)
In the fall, beavers spend weeks cutting, transporting and piling sticks and branches whose bark, twigs and leaves will hopefully provide them with sustenance through the winter. With no access to land once ice forms, beavers rely on the food that they have had the foresight to store on the bottom of the pond in the fall, as close to the main entrance to their lodge as possible. Initially the beavers dive down and stick the butt end of the branches into the mud. Once anchored, these branches form the base of a growing pile which often sticks out above the surface of the pond. (The portion of the pile above the water is not accessible to the beavers once the pond freezes.) According to beaver biologist Leonard Lee Rue, a beaver colony needs to store between 1,500 and 2,500 pounds of edible bark, twigs and leaves (this weight doesn’t include the wood, as they don’t eat wood) if it is to sustain them through the winter. As one would suspect, southern beavers do not need nor make winter food supply piles.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Beavers Refurbishing Lodge

10-14-13 refurbished beaver lodge 248This is the time of year when the industriousness of beavers can determine whether or not they survive through the winter. There are three major tasks for a beaver colony to tend to in the fall: refurbishing their lodge; strengthening and repairing their dam; and cutting and storing their winter food supply. They tend to perform these tasks in this sequence, tackling the lodge first. If the water level is high, the beavers will raise the floor of the lodge and the roof of the sleeping chamber. Every fall they add new material to the exterior of the lodge to strengthen the entire structure – typically sticks intertwined that create walls two feet thick or more. At this point the beavers coat the lodge with mud that they dredge up from around the base of the lodge (which greatly increases the depth of the water near the lodge). The apex of the lodge is not coated, allowing fresh air to filter down into the sleeping chamber. Once cold weather arrives, the mud hardens to the consistency of concrete, making the lodge is impenetrable to predators that can approach the lodge once the pond freezes. (In photo, note the fresh eastern hemlock branches and mud that have recently been added to the lodge.)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Mutual Grooming

8-1-13 beavers grooming each other IMG_2714Beavers spend a great deal of time tending to their coats, grooming several hours a day throughout the year. Grooming consists of removing sticks and debris that have become embedded in their fur, as well as applying oil from their anal glands to waterproof their fur. Waterproofing is essential, as it prevents the cold water from penetrating their fur. Typically they sit with their tail between their hind legs, stretched out in front of them, with their anal glands exposed. Beavers procure the oil with their front feet, and use all four feet to comb it through their fur. The two inside nails on both of their hind feet are split, increasing the efficiency with which they can apply the oil. Sometimes two beavers will groom each other, engaging in “mutual grooming.” The male and his offspring begin to groom each other when the kits are only two weeks old, yearlings and kits from three weeks on, and the mother and kits when the young are four weeks old. Mutual grooming continues as long as they are a family unit. ( I am humbled by the response to yesterday’s post. You will each be hearing from me soon. )


Owl Ears

3-26-13 barred owl ear IMG_7161It’s well known that owls have an acute sense of hearing — some species, such as the barn owl, hunt nocturnally by sound alone. An owl’s asymmetrically-placed ears are located beneath the feathers at the edge of its facial discs. This placement, along with the shape of the external ear canals, is thought to contribute to an owl’s keen ability to locate sound. The flesh-colored fold of skin that you see in front of this barred owl’s ear is movable, and reflects and concentrates sound waves coming from behind the bird.


Coyotes and Beavers

3-12-13 coyote & beaver lodge2 IMG_6223A study of coyote prey (through stomach contents) in the Adirondack Mountains of New York revealed that beavers were second only to white-tailed deer. This photograph shows that, possibly for the last time this winter, a coyote recently took advantage of a still-frozen-but-fast-thawing pond by walking across it in an attempt to reach an active beaver lodge. Once there the coyote attempted to dig into it in order to reach the inhabitants. A hard, two-to three-foot-thick wall of frozen mud, logs and sticks kept the beavers well protected, as it was designed to.


Raccoons Up & About

3-7-13 raccoon IMG_2452 copyWhile we don’t see raccoons much in the winter, it isn’t because they’ve been hibernating. Rather, during cold spells, they seek shelter, often in hollow trees, where they remain for up to a month at a time in a fairly lethargic state (but not true hibernation). If the temperature at night rises above freezing, raccoons are out foraging. Lately their tracks have been very evident, signaling that their nights of inactivity are coming to an end. There isn’t much food for them to find this time of year, so for the most part they are living off the fat that they accumulated last fall.


Porcupines Tapping Out

porcupine tap IMG_3494At least one porcupine got a jump on humans this sugaring season. A porcupine eats outer tree bark in order to access the phloem (layer of inner bark cells that transport nutrients) and cambium (produces phloem and xylem cells) layers of a tree, its primary winter diet. In eating these layers, the porcupine unintentionally cuts into the xylem, or sapwood, where water and dissolved minerals (sap) are transported between the roots and crown of the tree. Unintentionally, porcupines tap the trees whose phloem and cambium they eat. In this case, the weather had warmed up enough to cause pressure in the tree, which in turn caused the sugar maple’s sap to flow just as a hungry porcupine happened along. Soon thereafter, the temperature dropped, causing the sap to freeze, forming icicles. While they looked good enough to sample, one whiff of them told me that sap was not their sole ingredient! (They were located beneath the porcupine’s den in a hollow tree, from which urine flows freely.)


Follow

Get every new post delivered to your Inbox.

Join 2,893 other followers